Interior material, panel forming body, and manufacturing method for interior material

ABSTRACT

The present invention provides an interior material of an operator&#39;s cab of a work machine, the interior material comprising at least a structure member and a noise absorption layer, wherein the structure member has at least one rib which is formed on an inside surface of a base portion thereof and comes into intimate contact with an inside surface of an exterior material and a hermetically sealed hollow portion is formed by the rib in intimate contact with the exterior material, and the noise absorption layer is disposed on an outside surface of the structure member. With the interior material, a work environment in the operator&#39;s cab of the work machine can be enhanced by effectively suppressing the noise entering from an outside of the operator&#39;s cab.

TECHNICAL FIELD

The present invention relates to an interior material of an operator'scab for use in work machines, work vehicles, and the like such as civilengineering/construction, agricultural, and other industrial machinesand vehicles, and to a method of manufacturing the interior material.

BACKGROUND ART

In general, work machines include machines and vehicles for performingvarious types of works (hereinafter, referred to as work machines), forexample, a civil engineering /construction machine such as a hydraulicshovel and the like, an agriculture machine such as a tractor and thelike, a material handling machine, and other industrial machines,vehicles and the like. An operator's cab disposed to these work machinesis placed in a bad working environment with violent noise and vibration.

For example, there is a hydraulic shovel 100 as one of civilengineering/construction machines as shown in FIG. 8. In the hydraulicshovel 100, an upper pivot body 103 is pivotably disposed on a lowertraveling body 101 through a pivot mechanism 102. The upper pivot body103 is provided with power units such as a work machine 104, an engine108 and the like, and an operator's cab 110, and the like. Further, ingeneral, this type of the work machine 104 has an attachment 107attached thereto such as a boom 105 disposed to perform an up and downoperation, an arm 106 mounted at an extreme end of the boom 105 to pivotup and down, a bucket disposed at an extreme end of the arm 106, and thelike.

The operator's cab 110 is ordinarily formed in a box shape, and has afront window attached to a front surface and a window formed on a rearportion in a size as large as possible. Further, the operator's cab 110is also provided with a window in an upper half portion on a side wherethe work machine 104 is installed (on a right side in a travelingdirection of the vehicle) as shown in FIG. 8, and a door 111 is disposedto an opposite side of the window (on a left side in the travelingdirection of the vehicle). An operator enters and exits the operator'scab 110 by opening and closing the door 111.

In the hydraulic shovel 100, drive machines such as a vehicle-mountedengine 108 and the like are disposed rearward of the operator's cab 110.In addition, the work machine 104 disposed forward of the operator's cab110 performs work such as excavation, lifting of soil, and the like. Asa result, an inside of the operator's cab 110, in which the operatordrives the hydraulic shovel, has violent noise and vibration and isplaced in a very bad working environment. For this reason, there isconventionally required to improve dwelling comfort in the operator'scab by suppressing noise to the operator's cab 110 in order to improve aworking environment of the operator.

In contrast, for example, a passenger car is provided with noiseinsulation means for preventing noise from an engine into a compartment.As the noise insulation means, an action of bonding a noise insulationmaterial to partition parts, and the like is ordinarily employed. As amethod of attaching the noise insulation material, Japanese PatentApplication Laid-Open No. 2003-10967 (patent document 1) discloses amethod of manufacturing noise insulating body parts. In the method ofmanufacturing the noise insulating body parts, in order to fill bodyparts such as a dash lower with a noise insulation material, a noiseinsulation material is previously inserted into a molded vehicle partbefore it is foamed, the inserted noise insulation material is partlyfoamed by heat when the vehicle part is welded, and then the overallnoise insulation material is heated and foamed. Further, a plurality ofribs are disposed in a row in the dash lower along an extendingdirection thereof so that they act as fitting means and reinforcingmeans of the noise insulation material.

Further, for example, Japanese Patent No. 3280845 (patent document 2)proposes an interior material for a passenger car. In the interiormaterial for the passenger car, a plurality of fan-shaped continuousreinforcing ribs are disposed in contact with an inner surface of theinterior material that covers a space formed adjacent to a structuremember such as a pillar panel, a side roof and the like of the passengercar as well as additional ribs smaller than the reinforcing ribsinterposed between the reinforcing ribs as means for preventing noisesuch as a zoom generated when the passenger car travels.

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2003-10967-   Patent Document 2: Japanese Patent No. 3280845

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

When the method of filling vehicle parts with the noise insulationmaterial is employed to insulate noise as disclosed in the patentdocument 1 in a passenger car to which excellent dwelling comfort isrequired as described above, it is effective means to a portion such asthe dash lower whose space is formed relatively small. However, inconstruction machines such as a hydraulic shovel whose body is intenselyvibrated in its entirety as compared with passenger cars and violentnoise and vibration are transmitted from an engine mounted thereon,respective panel forming bodies that form an operator's cab are large insize as a whole due to a structure thereof, and further an assemblystructure of the body thereof is different from that of the passengercar. Accordingly, it is difficult to apply a system of the patentdocument 1 to work machines such as the construction machines and thelike.

Further, when two types of ribs are directly and alternately disposed toan interior material or to an exterior material to suppress generationof vibration as in the patent document 2, it is difficult to suppresssuch large noise as that generated in the work machines only by aprovision of the ribs.

That is, in the work machines with intense noise and vibration, it isdifficult to expect a sufficient noise damping effect only bycountermeasures employed in the passenger car such as filling an insideof a panel forming body that covers the outside of an operator's cabwith a material having an excellent noise insulation property orproviding the inside of the panel forming body with ribs, when time andeffort required to manufacture the panel forming body is taken intoconsideration.

Accordingly, an object of the present invention, which has been made toovercome the above problems, is to provide an interior material and apanel forming body of an operator's cab of a work machine that canimprove a working environment in the operator's cab by effectivelysuppressing noise entering the operator's cab from an outside thereof,and a method of manufacturing the interior material.

Means for Solving the Problems

To achieve the above object, a leading feature of the present inventionresides in an interior material of an operator's cab of a work machine,the interior material having at least a structure member and a noiseabsorption layer, wherein the structure member includes at least one ribwhich is formed on an inside surface of a base portion thereof and comesinto intimate contact with an inside surface of an exterior material, ahermetically sealed hollow portion is formed by the rib in intimatecontact with the exterior material, and the noise absorption layer isdisposed on an outside surface of the structure member.

Further, in the interior material of the present invention, it ispreferable that, in order to more effectively absorb entering noise(noise wave), an inside surface of the structure member and a part of asurface or an entire surface of the rib are provided with the noiseabsorption layer, and it is preferable, for example, that the insidesurface of the structure member confronting the exterior material isprovided with the noise absorption layer.

Further, when a noise insulation property of the interior material istaken into consideration in the present invention, it is preferable thatthe structure member is formed of any one of polyurethane,polypropylene, ABS resin, and AES resin, and it is preferable that thenoise absorption layer is a continuous foam body and/or a fiberaggregate formed of at least one of low repulsion urethane, semi-rigidurethane, PET (polyethylene terephthalate) resin, and polystyrene resin.

Further, in the present invention, it is preferable that a surface cladmaterial is attached to a surface of the noise absorption layer oppositeto the structure member, and, in particular, it is preferable that thesurface clad material is subjected to a dirt prevention treatment.

According to the present invention, there is provided a panel formingbody including the interior material and the exterior material of thepresent invention.

Next, there is provided a method of manufacturing an interior materialof an operator's cab of a work machine according to the presentinvention, the interior material having a structure member and a noiseabsorption layer disposed on an outside surface of the structure member,wherein the structure member has a rib which stands from an insidesurface of the base portion thereof and comes into intimate contact withan inside surface of an exterior material, and a hollow portion isformed by the rib in intimate contact with the exterior material. Aleading feature of the method resides in forming the structure memberhaving at least one rib in a desired shape by an injection moldingmethod; forming at least one hole portion in the structure member, thehole portion passing through the base portion from an outside surfacethereof to the inside surface thereof when or after the structure memberis molded; attaching the structure member in which the hole portion hasbeen formed to a mold; and molding a noise absorption layer on theoutside surface of the structure member using the mold by injecting amaterial constituting the noise absorption layer onto the outsidesurface of the structure member, and at the same time, forming the noiseabsorption layer on the inside surface of the structure member and on apart of the surface or an entire surface of the rib through the holeportion.

Further, it is preferable that the method of manufacturing the interiormaterial of the present invention includes, when the noise absorptionlayer is injection-molded: previously attaching the surface cladmaterial to a side of the mold confronting the outside surface of thestructure member; and injecting the material constituting the noiseabsorption layer into an interval between the structure member and thesurface clad material attached to the mold.

EFFECT OF THE INVENTION

The interior material of the operator's cab of the work machine of thepresent invention has at least the structure member and the noiseabsorption layer. The structure member includes at least one rib whichis formed on the inside surface of the base portion thereof and comesinto intimate contact with the inside surface of the exterior materialas well as the hermetically sealed hollow portion formed by the rib inintimate contact with the exterior material, and the noise absorptionlayer is disposed on the outside surface of the structure member.

That is, the interior material of the present invention can obtain avery excellent noise insulation effect by being simultaneously providedwith a function for suppressing vibration of the exterior material bythe rib in intimate contact with the exterior material and a functionfor absorbing the noise entered the hermetically sealed hollow portionof the structure member after it is diffusedly reflected and damped.

In addition, when the interior material of the present invention has thenoise absorption layer on the inside surface of the structure member andthe part of the surface of the rib, the noise which enters thehermetically sealed hollow portion of the structure member can be dampedby being diffusely reflected repeatedly in the hollow portion as well ascan be absorbed by the noise absorption layer on the inside surface ofthe structure member. Consequently, the interior material can obtain avery excellent noise insulation effect.

Further, in the present invention, when the structure member is formedof any one of polyurethane, polypropylene, ABS resin, and AES resin,these materials are excellent in molding easiness, and therefore, thestructure member can be easily and securely molded even if the interiormaterial has a complicated shape. Further, since the structure membermolded by the molding material has high rigidity, it can stably keep apredetermined shape.

Furthermore, when the noise absorption layer of the interior material isthe continuous foam body and/or the fiber aggregate formed of at leastone of low repulsion urethane, semi-rigid urethane, PET resin, andpolystyrene resin, it can be easily formed in conformity with the shapeof the structure member, and communication pores/ventilation spaces canbe easily formed therein. Accordingly, even if the noise absorptionlayer is thin in wall thickness and has complex and minute spaces formedtherein, it can very effectively absorb noise, whereby the noiseinsulation property of the interior material can be more enhanced.

The panel forming body of the present invention is provided with theinterior material having the excellent sound insulation effect asdescribed above. Thus, when it is attached to, for example, anoperator's cab of a work machine, the noise entering from the outside ofthe exterior material can be effectively suppressed, so that the workingenvironment in the operator's cab can be enhanced.

According to the method of manufacturing the interior material of theoperator's cab of the work machine of the present invention, theinterior material has a characteristic feature as described above. As aconsequence, even if the interior material of the operator's cab of thework machine of the present invention has a complex structure, it can beeasily and stably manufactured. In particular, in the manufacturingmethod of the present invention, the structure member is molded togetherwith the rib by the injection molding method, and thereafter, thematerial constituting the noise absorption layer is injected onto theoutside surface of the structure member after at least one hole portionis formed in the structure member such that it passes through the baseportion thereof from the outside surface to the inside surface.Accordingly, the noise absorption layer can be effectively formed on theinside surface of the structure member and on the part of the surface orthe entire surface of the rib through the hole portion at the same timethe noise absorption layer is molded on the outside surface of thestructure member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a panel forming body having aninterior material according to the present invention.

FIG. 2 is a schematic sectional view of a panel forming body having aninterior material of another mode according to the present invention.

FIG. 3 is a schematic explanatory view explaining a method of a noiseinsulation test.

FIG. 4 is a graph showing a result of the noise insulation test.

FIG. 5 is a schematic sectional view of a panel forming body having aninterior material of still another mode according to the presentinvention.

FIG. 6 is a schematic sectional view showing a more specific example ofa panel forming body having an interior material.

FIG. 7 is an explanatory view explaining a method of manufacturing aninterior material and a panel forming body.

FIG. 8 is a schematic view schematically showing a hydraulic shovel.

FIG. 9(a) is a perspective outside appearance view showing a specificapplication example of an interior material, and FIG. 9(b) is a backview when the interior material is observed from a back surface side.

REFERENCE NUMERALS

-   1 panel forming body-   1′ panel forming body-   1″ in panel forming body-   2 exterior material-   2′ inside surface of an exterior material-   3 interior material-   3′ interior material-   3″ interior material-   4 structure member-   4 a rib-   4′ inside surface of a structure member-   5 noise absorption layer-   6 surface clad material-   7 noise absorption layer-   7 a noise absorption layer-   8 hollow portion-   9 panel forming body-   10 interior material-   11 structure member-   11 a rib-   11′ base portion of a structure member-   12 hole portion-   13 noise absorption layer-   14 surface clad material-   15 air conditioning duct-   16 hollow portion-   18 lid member-   19 solid propagation sound-   20 noise entering a hollow portion-   50 mold-   51 upper mold-   52 lower mold-   54 mold-   55 upper mold-   56 lower mold

BEST MODE FOR CARRYING OUT THE INVENTION

A preferable embodiment of an interior material and a panel forming bodyof an operator's cab of a work machine according to the presentinvention as well as a method of manufacturing the interior materialwill be explained below in detail with reference to the drawings.

First, the interior material of the operator's cab of the work machineaccording to the present invention will be explained. FIG. 1 is aschematic sectional view of the interior material and the panel formingbody having the interior material according to the embodiment.

The panel forming body 1 for use in the operator's cab of the workmachine shown in FIG. 1 is composed of an interior material 3 which isdisposed on an operator's cab side, and an exterior material 2 which isdisposed in intimate contact with a rib 4 a of the interior material 3with the interior material 3 being integrated with the exterior material2. The exterior material 2 and the interior material 3 are assembled bybeing joined or bonded to each other at, for example, an extreme end ofa peripheral wall portion (not shown) of the interior material 3 so thatthey are not easily separated from each other. The panel forming body 1arranged as described above is disposed on side portions or a peripheryof an operator's cab of, for example, a work machine, and attached alonga frame constituting the operator's cab. In this embodiment, forexample, a hot rolled steel sheet can be used as the exterior material2.

The interior material 3 constituting the panel forming body 1 shown inFIG. 1 has a structure member 4, a noise absorption layer 5, and asurface clad material 6. At this time, an inside surface 4′ of thestructure member 4 has at least one rib 4 a in intimate contact with aninside surface of the exterior material 2, and a hermetically sealedhollow portion 8 is formed by the rib 4 a coming into intimate contactwith the exterior material 2. Note that it is sufficient if an extremeend of the rib 4 a standing from the base portion of the structuremember 4 is in intimate contact with the exterior material 2. That is,for example, the rib 4 a may be in intimate contact with the exteriormaterial 2 in a simply abutting state without being firmly fixedthereto, or the rib 4 a may be in intimate contact with the exteriormaterial 2 in a state that the rib 4 a is bonded thereto by an adhesiveand the like or in a state that it is joined to the exterior material 2through a material having a vibration damping effect including anelastic body such as rubber and a resin material. Further, a shape ofthe inside surface 4′ of the structure member 4 is not particularlylimited, and may be in a flat state or in a curved state.

In this embodiment, although the material of the structure member 4 isnot particularly limited, it is preferably formed of any one of, forexample, polyurethane, polypropylene, ABS resin, and AES resin. Thesematerials are excellent in molding easiness. For this reason, when thestructure member 4 is formed of the above materials, the interiormaterial 3 can be molded easily even if it has a complex shape. Further,since a molded structure member has high rigidity, it can keep apredetermined shape stably. Moreover, since the molding materials arealso excellent in a heat insulation property, a heat insulation effectcan be also expected. Thus, the molding materials can be veryeffectively used as the interior material for isolating the operator'scab of the work machine from the outside. In particular, when thestructure member 4 is formed of rigid foamed polyurethane, an excellentnoise insulation effect can be obtained because a solid propagation ofthe structure member can be effectively suppressed as described below indetail.

Further, in the interior material 3, the noise absorption layer 5 isformed on the outside surface of the structure member 4, and further thesurface clad material 6 is formed on the surface of the noise absorptionlayer 5 opposite to the structure member 4. Although the material of thenoise absorption layer 5 is not particularly limited, it is preferably alayer of a continuous foam body and/or a fiber aggregate formed of atleast any one of, for example, low repulsion urethane, semi-rigidurethane, PET resin, and polystyrene resin. The continuous foam body andthe fiber aggregate can be easily molded in conformity with thestructure member 4, and communication pores/ventilation spaces can beeasily formed therein. For this reason, since complicated minute spacesare formed in the noise absorption layer 5, noise which has entered thenoise absorption layer 5 can be very effectively absorbed even if it hasa small wall thickness. Note that, in this embodiment, the wallthickness of the noise absorption layer 5 is not particularly limitedand may be appropriately set according to an object.

Further, the surface clad material 6 can be appropriately selected andused from, for example, vinyl leather, a foamed polyolefin material (forexample, trade name “PEF” manufactured by Toray Industries, Inc.) havinga leather-like sheet on a surface, high density fiber fabric havingwater repellency, air permeability, and excellent feeling of touch on asurface, and the like. Note that when the polyolefin material having theleather-like sheet is used, a decoration property can be enhanced byforming crimped patterns on a surface thereof or forming anotherpatterns by emboss processing. Further, when the fiber fabric is used,the decorating property can be enhanced by color tone and inherentoutside appearance. Furthermore, when the surface clad material 6 issubjected to a dirt prevention treatment, the interior material can beprevented from becoming dirty and the surface of the interior material 3can be kept clean. Note that the surface clad material 6 may be formedon, for example, an outside surface of a peripheral wall portion of thestructure member 4, in addition to that it is formed on the noiseabsorption layer 5.

In the panel forming body 1 configured as described above, when noiseenters the inside of the operator's cab through the interior material 3from the outside of the exterior material 2, first, a part of the noiseis reflected on the outside surface of the exterior material 2 andremaining noise passes through an entire surface of the exteriormaterial 2 and enters the structure member 4. At this time, in theinterior material 3, the rib 4 a of the structure member 4 is inintimate contact with the exterior material 2. Consequently, thevibration of the exterior material 2 generated when the noise enters itcan be effectively suppressed, from which an excellent noise insulationeffect can be obtained.

In contrast, a part of the noise that has entered the structure member 4through the exterior material 2 is transmitted by a solid propagationthrough the inside of the rib 4 a that is in intimate contact with theexterior material 2, and most part of other noise 20 enters thehermetically sealed hollow portion 8 through the exterior material 2. Atthis time, solid propagation noise 19 propagating in the rib isgradually damped during the solid propagation in the rib, and absorbedby the sound absorption layer 5 disposed on the outside surface of thestructure member.

In contrast, the noise 20, which has entered the hermetically sealedhollow portion 8 through the exterior material 2, is gradually damped bybeing diffusely reflected (echoed) repeatedly on the inside surface 4′of the structure member 4, on the surface of the rib 4 a, and further onthe inside surface 2′ of the exterior material 2 in the hollow portion8, and thereafter absorbed by the noise absorption layer 5.

That is, according to the interior material 3 of this embodiment, thevibration of the exterior material 2 can be suppressed by the rib 4 a incontact with the exterior material 2, and the noise 19 which istransmitted by the solid propagation in the rib 4 a of the structuremember 4 can be damped and absorbed by the noise absorption layer 5.Further, the noise 20 which enters the hermetically sealed hollowportion 8 of the structure member 4 can be absorbed by the noiseabsorption layer 5 after it is diffusely reflected and damped. With thisoperation, a sound pressure level of the noise that enters from theoutside of the exterior material 2 can be greatly reduced by theinterior material 3. As a consequence, a very excellent noise insulationeffect can be obtained as compared with, for example, conventionallyused noise insulation means (for example, patent document 1) and noiseproof means (for example, patent document 2).

In particular, when the structure member 4 is composed of a materialwhich is excellent in a damping characteristic and can effectively dampsolid vibration, for example, rigid foamed polyurethane as describedabove, it is possible to accelerate damping of the noise 19 transmittedby the solid propagation in the rib 4 a, and therefore, a noiseinsulation effect of the interior material 3 can be more enhanced.

In contrast, according to the present invention, there can be providedan interior material 3′ having a noise absorption layer 7 on an insidesurface 4′ of a structure member 4 and on a part of the surface of a rib4 a as shown in, for example, FIG. 2 as an interior material of anothermode according to the embodiment. Further, there can be provided aninterior material 3″ having a noise absorption layer 7 on an insidesurface 4′ of a structure member 4 and on of an entire surface of a rib4 a as shown in, for example, FIG. 5 as an interior material of stillanother mode.

A panel forming body 1′ shown in, for example, in FIG. 2 has a sameconfiguration as the panel forming body 1 shown in FIG. 1 except that ithas the interior material 3′ having the noise absorption layer 7 on theinside surface 4′ of the structure member 4 confronting the insidesurface of an exterior material. The interior material 3′ configured asdescribed above has the noise absorption layer 7 on the inside surface4′ of the structure member 4 in a hollow portion 8. For this reason,when noise enters the hermetically sealed hollow portion 8 of thestructure member 4 from the outside of the exterior material 2, thenoise 20 which has entered the hollow portion 8 can be damped by beingdiffusely reflected repeatedly in the hollow portion 8 and absorbed bythe noise absorption layer 7 on the inside surface 4′ of the structuremember 4, whereby a very excellent noise insulation effect can beobtained.

Further, a panel forming body 1″ shown in FIG. 5 has the sameconfiguration as the panel forming body 1 shown in FIG. 1 except that ithas the interior material 3″ having noise absorption layers 7, 7′ on theinside surface 4′ of the structure member 4 and on the entire surface ofthe rib 4 a. Since, in the interior material 3″ configured as describedabove, the region of the noise absorption layer formed in a hollowportion 8 is more increased than the interior material 3′, the interiormaterial 3″ can absorb the noise which has entered the hollow portion 8by the noise absorption layers 7, 7′, so that a more excellent noiseinsulation effect can be obtained.

That is, provision of the noise absorption layer 7 on the inside surface4′ of the structure member 4 as described above can enhance the noiseinsulation effect by the interior material. Further, the noiseinsulation effect can be more enhanced by attaching the noise absorptionlayer 7 on the inside surface 4′ of the structure member 4 and theentire surface of the rib 4 a, whereby an interior material having avery excellent noise insulation effect can be obtained.

To examine the noise insulation characteristics of the interiormaterials according to the embodiment, a following noise insulation testwas executed based on a method of measuring an air noise insulationperformance of a construction member in a laboratory based on JIS A1416(ISO 140-3).

To briefly explain the method of the noise insulation test performedthat time, a noise insulation wall B composed of a concrete block wasinterposed between an anechoic chamber A and a reverberation chamber Cto partition them from each other as shown in, for example, FIG. 3, anda test panel forming body 1 was attached to the noise insulation wall B.A noise source (not shown) was disposed on a reverberation chamber Cside, a plurality of microphones G were disposed in the anechoic chamberA in confrontation with the test panel forming body 1, and a peripheryof the panel fitted to the wall B was filled with a joint to prevent aleakage of noise. In this state, a transmission loss was measured byusing 1/f noise (pink noise) as the noise source that is more weaken ina higher frequency in inverse proportion to a frequency.

In this noise insulation test, measurement was executed by using thepanel forming body 1 shown in FIG. 1 and the panel forming body 1′ shownin FIG. 2 as the test panel forming body. Note that, in the panelforming body 1 (FIG. 1) used this time, a hot rolled steel sheet of 4.5mm in thickness was used as the exterior material 2. Further, theinterior material 3 was arranged such that a base portion of thestructure member 4 had a thickness of 10 mm, the rib 4 a had a height of20 mm (substantially, a height of the hollow portion 8), and the noiseabsorption layer 5 had a thickness of 10 mm, and further trade name“PEF” (manufactured by Toray Industries, Inc.) was used as the surfaceclad material 6.

In addition, as the panel forming body 1′(FIG. 2), a panel forming bodyhaving a 5 mm thick noise absorption layer 7 formed on the insidesurface 4′ of the structure member 4 was used, in addition to a materialand a dimension of the panel forming body 1. For comparison, the noiseinsulation test was also executed to a specimen, which was composed of a4.5 mm thick hot rolled steel sheet having a 20 mm thick soundabsorption material formed of a PET fiber material and attached to onesurface of the sheet, and to a specimen composed of a 4.5 mm thicksimple hot rolled steel sheet (steel sheet having no sound absorptionmaterial attached thereto).

FIG. 4 is a graph showing results of these noise insulation tests.Further, to verify results of noise insulation effects obtained by thenoise insulation tests, FIG. 4 also shows a value obtained bycalculating a transmission loss of a 4.5 mm thick hot rolled steel sheetbased on a mass law calculation formula.

As apparent from the results of the tests shown in FIG. 4, it has beenfound that the panel forming body 1 having the hollow portion 8 formedby the interior material 3 as shown in FIG. 1 is more excellent in anoise insulation property than the simple steel sheet and the steelsheet having the noise insulation material attached thereto and has atransmission loss higher than a calculated value (shown by a brokenline) obtained by the mass law calculation formula in a region in which⅓ oct. center frequency is about 400 to 4000 Hz. Further, it has alsobeen confirmed that the panel forming body 1′ having the noiseabsorption layer 7 disposed on the inside surface 4′ of the structuremember 4 as shown in FIG. 2 has a noise insulation property moreexcellent than the panel forming body 1 of FIG. 1.

It has been confirmed from the results of the tests described above thatwhen the panel forming body 1 is composed of the interior material 3 asshown in FIG. 1 which has the hollow portion 8 hermetically sealed bybeing provided with at least one rib 4 a in intimate contact with theexterior material 2 and is provided with the noise absorption layer 5,noise entering from the outside of the exterior material 2 can be moreeffectively insulated than ever. Further, it has also been confirmedthat provision of the noise absorption layer 7 on the inside surface 4′of the structure member 4 as shown in FIG. 2 more enhanced the noiseinsulation effect of the interior material. It can be determined fromthe above results that more excellent noise insulation characteristicscan be obtained by disposing the noise absorption layer 7 on the insidesurface 4′ of the structure member 4 and on the surface of the rib 4 aas shown in, for example, FIG. 5.

Next, more specific embodiments of the interior material and the panelforming body according to the present invention will be explained indetail with reference to FIG. 6. FIG. 6 is a schematic sectional viewschematically showing an example of a panel forming body for use in anoperator's cab of a work machine.

A panel forming body 9 shown in FIG. 6 is configured by attaching anexterior material 2 composed of a hot rolled steel sheet to an interiormaterial 10. At this time, the interior material 10 is formed in anoutside dimension necessary to an interior of the operator's cab and hassuch a structure that an air conditioning duct 15 is assembledintegrally therewith at a predetermined position. In the interiormaterial 10, a structure member 11 for forming a basic bone structurethereof is molded of rigid foamed urethane, and a plurality of ribs 11 aare formed on an inside surface of the structure member 11 integrallytherewith vertically with respect to a base portion 11′ of the structuremember 11. Hermetically sealed hollow portions 16 are formed by bringingextreme ends of the ribs 11 a into intimate contact with the exteriormaterial 2.

Further, a plurality of holes 12, which pass through the base portion11′ from an outside surface thereof to an inside surface thereof, areformed in the structure member 11 such that a noise absorption layer 13can be effectively formed on the inside surface of the structure member11 in, for example, a process for manufacturing the interior material10. Note that a lid member 18 is disposed to the interior material 10 asa member for closing an open portion of a duct forming section that isused to form the air conditioning duct 15.

In the above-described structure member 11, the noise absorption layer13 is formed on each of the outside surface of the structure member 11(surface of the structure member 11 opposite to an exterior material 2side) and the inside surface thereof (surface of the structure member 11confronting the exterior material 2) integrally therewith in apredetermined thickness. A foamed layer of a continuous foam memberformed of any one of, for example, low repulsion urethane, semi-rigidurethane, PET resin, and polystyrene resin may be used as the noiseabsorption layer 13. Further, a surface clad material 14 is disposed onan operator's cab side surface of the noise absorption layer 13. Forexample, trade name “PEF” (manufactured by Toray Industries, Inc.) maybeused as the surface clad material 14.

The interior material 10 configured as described above has a functionfor suppressing the vibration of the exterior material 2 generated bythe ribs 11 a, a function for damping the noise that is transmitted bythe solid propagation in the ribs 11 a and absorbing the noise by thenoise absorption layers 13, and a function for diffusely reflecting anddamping the noise that has entered the hollow portions 16 as well asabsorbing the noise by the noise absorption layers 13 as describedabove. Accordingly, even if noise enters from, for example, the outsideof the exterior material 2, the sound pressure level of the noise can beeffectively reduced by the interior material 10.

Accordingly, in the operator's cab of the work machine externallycovered with the panel forming body 9 having, for example, the interiormaterial 10 as described above, an outside wall of the operator's cabcan be surrounded by the panel forming body 9 except an open portion towhich a window glass and the like are attached. With this arrangement,even in a place where noise is severely generated by an engine beingdriven, jobs such as excavation and lifting of soil, and the like, noiseentering the operator's cab from the outside can be greatly reduced bythe excellent noise insulation effect of the interior material 10. As aresult, an influence of noise applied to an operator in the operator'scab can be greatly reduced, thereby a working environment can besignificantly enhanced.

Further, since the interior material 10 according to the presentembodiment can not only obtain the excellent noise insulation effect asdescribed above but also can be molded to any arbitrary shape, a shapeof the panel forming body 9 can be optionally designed according to awork machine to which the panel forming body is installed. Further,since the surface clad material 14 is disposed on an operator's cab sidesurface of the interior material 10, an effect of obtaining an excellentdwelling comfort can be also obtained by improving a decoration propertyand a feeling.

A specific application example, to which the interior material accordingto the embodiment described above is actually applied, will be explainedhere with reference to FIG. 9. Note that FIG. 9(a) is a perspectiveoutside appearance view of the specific application example of theinterior material according to the embodiment, and FIG. 9(b) is a backview when the interior material is observed from a back surface side.

An interior material 35 shown in FIG. 9 is disposed on a right side ofan operator's cab in a construction machine, and includes a noiseabsorption layer (not shown) between a surface clad material 39 disposedon the operator's cab side and a structure member 36. A surface cladmaterial having, for example, a good feeling of tough and an excellentdesign effect is used as the surface clad material 39 of the interiormaterial 35 disposed on the operator's cab side.

In addition, in the structure member 36, a plurality of ribs 31 a aredisposed so as to come into intimate contact with an exterior material(not shown) attached to the interior material 35. Disposing the ribs 31a as described above permits hermetically sealed hollow portions to beeasily formed when the exterior material is attached and provides theinterior material 35 with strength by which an overall shape thereof canbe stably maintained.

Further, an air conditioning duct 37 is formed in the structure member36 as shown in FIG. 9(b) (note that FIG. 9(b) shows a state that no lidmember is attached). The air conditioning duct 37 has a duct attachmentport 29 to be connected to an air conditioner (not shown) and air supplyopenings 30, 30′, 30″ formed at arbitrary positions. A louver (notshown) is disposed to each of the air supply openings 30, 30′, 30″ whichare integrally formed therewith or independently manufactured. Further,closed spaces 38 may be formed to the structure member 36, if necessary.

Furthermore, the interior material 35 may be integrally formed withaccessories attachment portions, for example, a motor assembly portion31 and the like, an ash tray assembly portion 32, a cup holderattachment portion 33, and the like at arbitrary positions.

Then, when the interior material 35 configured as described above isattached to the operator's cab of the work machine, the noise thatenters the operator's cab from the outside can be greatly reduced by theexcellent noise insulation effect of the interior material 35, wherebythe work environment in the operator's cab can be significantlyenhanced.

Next, a method of manufacturing the interior material 10 and the panelforming body 9 according to the embodiment will be explained in detailwith reference to FIG. 7. FIG. 7 is an explanatory view schematicallyexplaining the method of manufacturing the interior material 10 and thepanel forming body 9.

First, as shown in FIG. 7(a), a mold 50 is prepared to mold thestructure member 11 of the interior material 10. The mold 50 is composedof an upper mold 51 and a lower mold 52 and designed with high accuracysuch that the structure member 11 having a predetermined shape and atleast one rib 11 a can be molded. The structure member 11 having the rib11 a is molded with the mold 50 by injecting a material for constitutingthe structure member 11 (resin material) into a space (cavity) formed bythe upper mold 51 and the lower mold 52 by an injection molding method.

To explain a case that the structure member 11 is formed of, forexample, rigid foamed polyurethane, more specifically, isocyanate and areactive resin material of polyol containing a foaming agent which areseparately accommodated in material tanks are first supplied into amixing head (not shown) disposed just in front of the mold 50 inpredetermined amounts respectively and mixed therein. When the reactiveresin material is poured into the mold 50 at low pressure, a mechanismfor rotating a stirring blade by an electric motor is disposed in, forexample, the mixing head and the reactive resin material is mixed whilebeing stirred.

In contrast, when the reactive resin material is poured at highpressure, no stirring mechanism is necessary, and the reactive resinmaterial is mixed by collision. Thereafter, the mixed reactive resinmaterial is injected into the cavity of the mold 50 from the mixing headat low temperature. At the time, it is possible to supply the polyolpreviously containing water as the foaming agent into the mixingchamber, or a catalyst, a curing agent, a foam stabilizer, and the likemay be further added to the reactive resin material, if necessary.

Then, the reactive resin material supplied into the mold 50 can befoamed at low temperature with its reaction heat by being reacted in thecavity rapidly. Consequently, the structure member 11 composed of therigid foamed polyurethane and having at least one rib 11 a can bemanufactured.

At this time, when the mold 50 is designed such that a lid member 18used to form the air conditioning duct 15 described above can be alsomolded at a same time, the structure member 11 and the lid member 18 canbe effectively molded by an injection molding process executed once.

Thereafter, the structure member 11 and the lid member 18 each having adesired shape can be obtained by taking out a molded body from the mold50 and cutting off unnecessary portions. Note that at least one holeportion 12 passing through a base portion of the structure member 11from an outside surface to an inside surface is previously provided tothe structure member 11 before a noise absorption layer described belowis molded. Incidentally, the hole portion 12 maybe formed when thestructure member 11 is molded. For example, a projecting portion whoseend is in intimate contact with the lower mold 52 (or with the uppermold 51) is formed to the upper mold 51 (or to the lower mold 52) at aportion where the rib 11 a of the structure member 11 is not disposed.

Next, the surface clad material 14 is manufactured to a predeterminedthickness by a thermoforming method such as vacuum forming and the like.The method of manufacturing the surface clad material 14 is notparticularly limited and may be manufactured by using a same method asthat of a conventional method.

Subsequently, as shown in FIG. 7(a), a mold 54 composed of an upper mold55 and a lower mold 56 which are designed in predetermined shapes tomold the noise absorption layer 13, is prepared, the structure member 11with the rib 11 a molded previously is attached to the upper mold 55,and the surface clad material 14 is attached to the lower mold 56 on aside thereof confronting the outside surface of the structure member 11.At this time, the structure member 11 can be easily attached to theupper mold 55 by, for example, attaching a magnet to the upper mold 55and attaching a metal clip and the like to the structure member 11. Incontrast, the noise absorption layer 13 can be attached to the lowermold 56 in a very intimate contact state by, for example, forming asingle or a plurality of openings as required to the lower mold 56 sothat they pass through the lower mold 56 from the outside thereof to thesurface thereof in contact with the surface clad material 14, connectingthe openings to a suction mechanism, and sucking the air in theopenings.

After the structure member 11 and the surface clad material 14 areattached to the upper mold 55 and the lower mold 56, respectively, amaterial constituting the noise absorption layer 13 (resin material) isinjected into a cavity formed between the structure member 11 and thesurface clad material 14 to form the noise absorption layer 13 betweenthe structure member 11 and the surface clad material 14 as shown inFIG. 7(c). At this time, the noise absorption layer 13 can be alsomolded simultaneously on the inside surface of the structure member 11by supplying the resin material from the outside surface side to theinside surface side of the structure member 11 through the hole portion12 formed in the structure member 11. Note that, when, for example, thenoise absorption layer 13 is formed on the inside surface of thestructure member 11 and the entire surface of the rib, it is necessaryonly to change a shape of the cavity formed in the upper mold 55.

A molded product, in which the structure member 11, the noise absorptionlayer 13, and the surface clad material 14 are integrated, can beobtained by injection-molding the noise absorption layer 13 as describedabove. Thereafter, the interior material 10 according to the embodimentcan be obtained by, for example, bending a portion of the surface cladmaterial 14 protruding from the noise absorption layer 13 to a noiseabsorption layer 13 side and bonding the portion. Even if, for example,the structure member 11 and the noise absorption layer 13 havecomplicated shapes, the interior material 10 can be obtained stably atlow cost by manufacturing the interior material 10 as described above.

In the interior material 10 obtained as described above, the lid member18, which has been molded simultaneously at a time of molding thestructure member 11 previously, is joined to a released portion of aduct forming section by using an adhesive and the like to form the airconditioning duct 15. Thereafter, the interior material 10 can beintegrated with the exterior material 2 by fixedly attaching an extremeend of a peripheral wall portion of the interior material 10 to theexterior material 2 by an adhesive and the like.

At this time, when, for example, an attachment seat previously formed onan exterior material 2 side is coupled with the extreme end of theperipheral wall portion of the interior material 10 by using a fastener,the interior material 10 can be more strongly joined to the exteriormaterial 2. In addition to the above mentioned, the interior material 10can be also integrated with the exterior material 2 by providing theexterior material 2 with, for example, an attachment seat piece of aclip and fitting the attachment seat piece to a metal clip previouslyattached to the structure member 11.

At this time, it is sufficient for the rib 11 a standing from the insidesurface of the structure member 11 to come into intimate contact withthe exterior material 2, and the rib 11 a may be fixedly attached to theexterior material 2 by an adhesive or may be simply abutted against theexterior material 2 according to an object. The panel forming body 9excellent in a noise insulation property can be easily manufactured atlow cost by integrating the interior material 10 with the exteriormaterial 2 as described above.

Note that a case in which the noise absorption layer 13 is formed on theinside surface of the structure member 11 by forming the hole portion 12in the structure member 11 has been explained above. However, as anothermethod, the noise absorption layer 13 can be also formed by, forexample, coating the surface of the inside surface of the structuremember 11 and the part of the surface or the entire surface of the ribwith the noise absorption layer 13 by using a spray after the structuremember 11 is molded. Further, when the noise absorption layer 13 isformed of, for example, a continuous foam body, the noise absorptionlayer 13 can be formed by making use of foam in situ. In contrast, whenthe noise absorption layer is formed on neither the inside surface ofthe structure member 4 nor the surface of the rib as in, for example,the panel forming body 1 shown in FIG. 1, the process for forming thehole portion can be omitted.

INDUSTRIAL APPLICABILITY

The interior material of the present invention can be applied to aninterior material of an operator's cab of work machines, work vehicles,and the like such as civil engineering/construction, agricultural, andother industrial machines, vehicles.

1. An interior material of an operator's cab for a work machine,comprising at least a structure member and a noise absorption layer,wherein the structure member has at least one rib which is formed in theinside surface of a base portion thereof and comes into intimate contactwith an inside surface of an exterior material, a hermetically sealedhollow portion is formed by the rib in intimate contact with theexterior material, and the noise absorption layer is disposed on anoutside surface of the structure member.
 2. The interior materialaccording to claim 1, wherein the inside surface of the structure memberand a part of the surface or an entire surface of the rib are providedwith the noise absorption layer.
 3. The interior material according toclaim 2, wherein the inside surface of the structure member confrontingthe exterior material is provided with the noise absorption layer. 4.The interior material according to claim 1, wherein the structure memberis formed of any one of polyurethane, polypropylene, ABS resin, and AESresin.
 5. The interior material according to any of claims 1 to 3,wherein the noise absorption layer is a continuous foam body and/or awoolie fiber aggregate formed of at least one of low repulsion urethane,semi-rigid urethane PET resin, and polystyrene resin.
 6. The interiormaterial according to claim 1, wherein a surface clad material isattached to a surface of the noise absorption layer opposite to astructure member side.
 7. The interior material according to claim 6,wherein the surface clad material is subjected to a dirt preventiontreatment.
 8. A panel forming body, comprising the interior material andthe exterior material according to any of claims 1 to
 3. 9. A method formanufacturing an interior material of an operator's cab for a workmachine, the interior material comprising at least a structure memberand a noise absorption layer disposed on an outside surface of thestructure member, wherein the structure member has a rib which standsfrom an inside surface of a base portion thereof and comes into intimatecontact with an inside surface of an exterior material, and ahermetically sealed hollow portion is formed by the rib in intimatecontact with the exterior material, the method comprising: forming thestructure member having at least one rib in a desired shape by aninjection-molding method; forming at least one hole portion in thestructure member, the hole portion passing through the base portion froman outside surface thereof to the inside surface thereof when or afterthe structure member is molded; attaching the structure member in whichthe hole portion has been formed to a mold; and molding a noiseabsorption layer on the outside surface of the structure member usingthe mold by injecting a material constituting the noise absorption layeronto the outside surface of the structure member, and at the same time,forming the noise absorption layer on the inside surface of thestructure member and on a part of a surface or an entire surface of therib through the hole portion.
 10. The method for manufacturing aninterior material according to claim 9, wherein when the noiseabsorption layer is (reaction) injection-molded (RIM): previouslyattaching a surface clad material to a side of the mold confronting theoutside surface of the structure member; and (reaction) injecting thematerial constituting the noise absorption layer into an intervalbetween the structure member and the surface clad material attached tothe mold.